Deciduous tooth crown measurements were investigated among the inhabitants of the Japanese islands over the past 4000 years. Mesiodistal and buccolingual crown diameters were measured in Neolithic Jomon, Aeneolithic Yayoi (divided into the samples from Tanegashima island and from other western Japanese sites), protohistoric Kofun, medieval, early modern Edo, modern Japanese and early modern Sakhalin Ainu samples. Overall deciduous tooth size decreased in the order of Tanegashima Yayoi, Yayoi, Jomon, Kofun, Edo, modern, medieval, and Sakhalin Ainu samples. The deciduous tooth size of the Jomon sample was larger than that of the modern Japanese, opposite to the relationship in their permanent dentition found by Brace and Nagai (1982). Diachronic size change of the Yayoi and post-Yayoi Japanese deciduous teeth was similar to that of their permanent teeth disclosed by Matsumura (1994). There was no apparent distinction between the Jomon and Yayoi samples, both in overall tooth size and in the proportion of tooth size. The Jomon and Tanegashima Yayoi samples had relatively larger deciduous teeth than the Yayoi and post-Yayoi Japanese samples when compared with their permanent teeth. It is likely that there was a difference in dental developmental pattern between the two groups.

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The dental morphology of the outer enamel surface (OES) is basically determined by the form of the dentino-enamel junction (DEJ) and the thickness of the enamel substance covering the DEJ. In our series of studies of morphological traits observed on the DEJ of deciduous molars (Sasaki, 1997; Sasaki and Kanazawa, 1999, 2000), we demonstrated that the traits are observed clearly on the DEJ as a distinct ridge or a process, even when they are not distinct on the OES. In this paper, we report characters originating from the buccal cingulum, the occurrence of occlusal ridges, and cusp number on the OES and DEJ of the upper first deciduous molar. The combined frequencies of (+) and (++) morphology of several traits were as follows: buccal cingulum: 62.2% (DEJ) and 15.4% (OES), mesiobuccal marginal ridge: 79.1% (DEJ) and 52.3% (OES), distobuccal marginal ridge: 33.9% (DEJ) and 7.7% (OES), mesiobuccal tubercle: 86.7% (DEJ) and 61.7% (OES), crista obliqua: 80.0% (DEJ) and 72.5% (OES), trigonal hypocone crest: 36.4% (DEJ) and 4.6% (OES). The frequencies of trait occurrence on the DEJ were higher than on the OES, because the original characters were not obscured by the enamel. Although previous observers had different opinions concerning the number of cusps of the upper first deciduous molar, three or four cusps were found on the DEJ suggesting that this tooth is more morphologically differentiated than the successional first premolar tooth. The results of this study suggested that phylogenetically conservative crown characters were retained more frequently in the anterior molar of the primary dental series from dm¹ to M².

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On the assumption that the degree of variation in a morphological character is related to its adaptive or functional significance, it was examined, utilizing fluctuating asymmetry and the coefficient of variation, whether there are any differences in adaptive or functional significance between deciduous teeth and the corresponding permanent teeth. Pitman's tests objectively show that the maxillary lateral permanent incisor is particularly variable, and its precursor, the maxillary lateral deciduous incisor, is as stable as the maxillary central deciduous incisor. This stability in size of the maxillary lateral deciduous incisor suggests that the battery of deciduous incisors has some important function which is not shared with the permanent incisors but is required for the infant period during which only the deciduous incisors are present.

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The allometric relationship between the second deciduous molar (dm2), the first permanent molar (M1), and body weight was investigated in catarrhine primates, including fossil hominid taxa. In this study, tooth and body weight measurements were compared in 14 species of hominoids and 11 species of cercopithecids. In all species, the mesiodistal and buccolingual crown diameters of dm2 were smaller than those of M1. The tooth crown area (mesiodistal crown diameter multiplied by buccolingual crown diameter) was used as the measure of tooth size. Allometric coefficients were computed as the slope of rectilinear functions of the logarithmically transformed data. Allometric scaling of tooth crown area to body weight showed isometry (the slopes ranged from 0.593 to 0.700). The allometric coefficients were slightly larger in M1 than in dm2, and were larger in the mandible than in the maxilla, but these differences were not significant. Both hominoids and cercopithecids were close to the regression line in both dm2 and M1, but Australopithecus species were peculiar that they have large permanent and deciduous molars in comparison to body weight, with A. boisei having the largest molars. These results indicated that the tooth crown size of dm2 scales to body weight in the same pattern as in the M1. The allometric scaling of the tooth crown area of dm2 to that of M1 showed negative allometry in both the maxilla and mandible, but these slopes were nearly 1.000 (0.932 in the maxilla and 0.954 in the mandible). Both hominoids and cercopithecids lay close to the regression line, indicating that the size of dm2 is closely related to that of M1.

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To analyze age-related changes in the total number of muscle fibers, the changes of the cross-sectional area of the anterior tibial muscle and the decrement rates of the total round number of muscle fibers were analyzed in male human subjects between 40 and 90 years of age. The results of the analysis in the age group 20s were used as controls. The atrophy rate of the muscle cross-sectional area ranged from 20.6% to 64.8% after the age of 40. The decrement rate of the total number of muscle fibers ranged from 6.0% to 40.5% after the age of 60. These findings and observations showed that the anterior tibial muscle showed markedly regressive change in male subjects after the age of 60.

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A case of expeditionary ranging, ranging extensively out of the original home range, was observed in a Japanese macaque troop in Hieizan. Their original home range covered 499ha, and during the one-month expedition, they ranged as far as 12km from it. This troop did not suffer any demographic or environmental changes preceding the expedition. The distribution pattern of crops, distributed in thin, long patches along the edges of forest, and lack of adjacent troops seem to have facilitated the extensive expedition by this troop.

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This study investigates some aspects of skeletal and dental paleo-pathology, including cribra orbitalia, dental enamel hypoplasia, trauma, osteoarthritis, periostitis and osteomyelitis. The sample consists of the skeletal remains of 33 individuals from the medieval and early modern periods, found on Ishigaki Island, Ryukyu Islands, Japan. High frequencies of cribra orbitalia and enamel hypoplasias suggest that the Ishigaki people may have experienced many severe nutritional deficiency stresses, infectious diseases, and/or parasitism during early childhood. This study further reports a markedly high frequency of periostitis and two cases of osteomyelitis in bones of the lower leg, probably the result of a specific infection, such as treponematosis.

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